Effective rehabilitative treatments for adult offenders have the potential to ameliorate offenders' extensive psychological and behavioral problems, increase the probability of stable, productive social adjustment upon release from criminal justice supervision, reduce reoffense rates, and decrease the burden on human service agencies. The large body of research on the effectiveness of such treatment, however, has not been well integrated and analyzed for purposes of identifying and applying "best practices" to the steadily increasing populations of adult offenders in the criminal justice system. The project proposed here is a comprehensive meta-analysis of experimental and quasi-experimental research oriented toward identification of the program configurations likely to produce the most positive outcomes in practical application. The major objectives of this project are as follows: 1. To assess the effects of rehabilitative treatment for adult offenders on multiple outcomes, including psychological functioning, behavioral problems, social relations, substance use, employment, and reoffending. 2. To determine the comparative effectiveness of different treatment types, circumstances, formats, settings, dosage, and implementation with an emphasis on identifying the distinctive characteristics of the most effective interventions. 3. To determine the comparative effects of different treatments for different offenders so that especially effective matches between type of treatment and type of offender can be identified. 4. To examine the relationships between the changes produced by effective rehabilitative treatments on each major type of outcome and those produced on other outcomes. In particular, to determine which treatment-induced changes are most closely associated with reductions in reoffending and thus help identify the pathways through which the treatment may have effects on criminal and antisocial behavior.